Perched on Mahee Island in Strangford Lough, the ruins of Mahee Abbey — also known as Nendrum Monastery — are among the oldest ecclesiastical remains in Ireland, dating as far back as the 5th century. Founded by St. Mochaoi, the monastery became a centre of learning and spiritual devotion, its monks living simple lives of worship and manual labour, cut off from the mainland save for a tidal causeway.

But today, long after its stone walls began to crumble, Mahee Abbey is known not just for its history — but for its hauntings.

Locals and visitors have reported eerie encounters at the site, including sightings of shadowy figures cloaked in robes, drifting silently through the abbey grounds. Some claim to have felt a heavy atmosphere descend without warning, followed by a chilling sense of being watched. According to legend, up to nine spirits are said to haunt the island — the restless shades of former monks, disturbed after the removal of sacred relics from the site during later centuries.

These monks, so the story goes, had dedicated their lives to quiet service. But when their holy artefacts were taken, their connection to the divine was broken, leaving them trapped between this world and the next. Some believe their ghostly presence is a form of silent protest — a yearning for the sacred harmony that once graced the island.

But Mahee Abbey is not without its stranger tales.

One enduring legend speaks of a mermaid — a creature said to dwell in the surrounding waters of Strangford Lough. It is said that she once emerged near the island and began singing a haunting, beautiful melody. One of the monks, entranced by her song, fell under her spell and wandered toward the shore, abandoning his post and prayers. As he neared the water’s edge, prepared to follow her into the depths, the distant toll of the matins bell — the early morning call to prayer — rang out across the lough. The sound broke the enchantment, and the monk, now pale and shaken, turned back to the monastery. He never spoke of what he saw, but others whispered of the sea-spirit with the voice that could drown a man’s soul.